Teen members of a group of archaic humans, Lynx and Quiller, flee the increasing coldness and monstrous predators for a new land, where they meet a strange old man who tells them how to save the world. One thousand years in the future: the zyme, a thick blanket of luminous green slime, covers the oceans; glaciers rise over the continents. Old stories say that the Jemen, godlike beings from the past, realized their efforts to halt global warming had...